The phylogenetic position of the enigmatic Assam day gecko Cnemaspis cf. assamensis (Squamata: Gekkonidae) demonstrates a novel biogeographic connection between Northeast India and south India-Sri Lanka

Abstract

Northeast Indian biodiversity has long been considered to have a stronger affinity to Southeast Asian rather than Peninsular Indian fauna, however, few molecular phylogenetic studies have explored this hypothesis. In Asia, the polyphyletic gekkonid genus Cnemaspis sensu lato is comprised of two distantly related groups; one primarily from South Asia with some members in Southeast Asia, and the other exclusively from Southeast Asia. Cnemaspis assamensis is a systematically obscure and geographically isolated species (>1400 km from its nearest congeners) from the Brahmaputra River Valley in Northeast India. We provide the first molecular phylogenetic assessment of this species based on a partial ND2 gene fragment. Cnemaspis assamensis is determined to be a deeply divergent (Oligocene) member of the South Asian radiation and is sister to the podihuna clade which is endemic to Sri Lanka. The biogeographic implications of this find are discussed and this is suspected to represent a rare example of true disjunction between the wet zones of Northeast India and southern India/Sri Lanka. These results further emphasise the importance of Northeast India as a refuge for unique ancient faunal lineages.